A variety of phase change materials available are well known for their thermal characteristics in that during their phase change stage they can absorb or release the latent heat while the temperature of the material is kept constant. Textiles and other products incorporated with the phase change materials, especially in the microencapsulated forms, may establish a microclimate surrounding the modified goods in the temperature ranges of the melting points of the employed phase change materials (PCMs) and so may meet the requirement for comfort. The use of microencapsulated PCMs may be found in U.S. Pat. Nos. 4,756,958 and 5,290,904.
U.S. Pat. Nos. 5,456,852 and 5,916,478 both describes processes of microcapsule manufacturing employing in situ polymerization, in which formaldehyde used may impose an environmental danger.
Examples of useful inherently flame retardant phase change materials may include halogenated paraffins having 10 to 22 carbon atoms and, more specifically, mono or poly-chlorinated and brominated paraffins such as bromooctadecane, bromopentadecane, bromononodecane, bromoeicosane, bromodocosane, and so on.
Throughout the investigation of the present invention it is found that the micro-encapsulation of paraffin compounds is much more difficult than the relative processes for the other core materials mainly due to the unique characteristics of paraffin compounds.